scholarly journals Crystallization Behavior and Mechanical Properties of Poly(ε-caprolactone) Reinforced with Barium Sulfate Submicron Particles

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2368
Author(s):  
Hegoi Amestoy ◽  
Paul Diego ◽  
Emilio Meaurio ◽  
Jone Muñoz ◽  
Jose-Ramon Sarasua
Keyword(s):  
Barium Sulfate ◽  
Thermal Studies ◽  
Polarized Light ◽  
Optical Microscope ◽  
Submicron Particles ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Nucleation Effect ◽  
Crystal Fraction ◽  
Light Optical Microscope

Poly(ε-caprolactone) (PCL) was mixed with submicron particles of barium sulfate to obtain biodegradable radiopaque composites. X-ray images comparing with aluminum samples show that 15 wt.% barium sulfate (BaSO4) is sufficient to present radiopacity. Thermal studies by differential scanning calorimetry (DSC) show a statistically significant increase in PCL degree of crystallinity from 46% to 52% for 25 wt.% BaSO4. Non-isothermal crystallization tests were performed at different cooling rates to evaluate crystallization kinetics. The nucleation effect of BaSO4 was found to change the morphology and quantity of the primary crystals of PCL, which was also corroborated by the use of a polarized light optical microscope (PLOM). These results fit well with Avrami–Ozawa–Jeziorny model and show a secondary crystallization that contributes to an increase in crystal fraction with internal structure reorganization. The addition of barium sulfate particles in composite formulations with PCL improves stiffness but not strength for all compositions due to possible cavitation effects induced by debonding of reinforcement interphase.

Crystalline Morphology and Crystallization Behavior of Poly(Trimethylene Terephthalate)/Functionalized Graphene Oxide Nanocomposites Prepared by Melt Compounding

2019 ◽  
Vol 814 ◽  
pp. 96-101
Author(s):  
Kun Yan Wang
Keyword(s):  
Graphene Oxide ◽  
Crystallization Behavior ◽  
Optical Microscope ◽  
Degree Of Crystallinity ◽  
Functionalized Graphene ◽  
Crystalline Morphology ◽  
Scanning Calorimetry ◽  
Functionalized Graphene Oxide ◽  
Melt Compounding ◽  
Trimethylene Terephthalate

Poly (trimethylene terephthalate) (PTT)/functionalized graphene oxide (fGO) nanocomposites were prepared by melt compounding. The crystalline morphology and crystallization behavior of PTT/fGO with different amounts of fGO were investigated by differential scanning calorimetry (DSC) and polarizing optical microscope (POM). The results show that the crystallization peak shifts to higher temperature after adding fGO, indicating that fGO have a nucleating effect on PTT. The crystallization temperature of nanocomposites increases with increasing content of fGO. The XRD pattern of PTT/fGO nanocomposites almost no change that indicated the degree of crystallinity of the PTT matrix remained unaffected by the addition of fGO. The nanocomposite revealed integrated Maltese crossed spherulitic morphologies. When adding 1% fGO to the PTT, big-sized PTT spherulites occurred and small-sized PTT spherulites were formed around the big-sized PTT spherulites which indicated that the mechanism of nucleation is changed.

scholarly journals Non-Isothermal Crystallization Kinetics of Injection Grade PHBV and PHBV/Carbon Nanotubes Nanocomposites Using Isoconversional Method

2020 ◽  
Vol 4 (2) ◽  
pp. 52
Author(s):  
Thaís Larissa do Amaral Montanheiro ◽  
Beatriz Rossi Canuto de Menezes ◽  
Larissa Stieven Montagna ◽  
Cesar Augusto Gonçalves Beatrice ◽  
Juliano Marini ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Model Fitting ◽  
Polarized Light ◽  
Isoconversional Method ◽  
Degree Of Crystallinity ◽  
Gamma Aminobutyric Acid ◽  
Scanning Calorimetry ◽  
Kinetics Of

Carbon nanotubes (CNT)-reinforced polymeric composites are being studied as promising materials due to their enhanced properties. However, understanding the behavior of polymers during non-isothermal crystallization is important once the degree of crystallinity and crystallization processes are affected when nanoparticles are added to matrices. Usually, crystallization kinetics studies are performed using a model-fitting method, though the isoconversional method allows to obtain the kinetics parameter without assuming a crystallization model. Therefore, in this work, CNTs were oxidized (CNT-Ox) and functionalized with gamma-aminobutyric acid (GABA) (CNT-GB) and incorporated into a poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) matrix. The influence of the addition and functionalization of CNT in the crystallization kinetics of PHBV was evaluated using the isoconversional method with differential scanning calorimetry (DSC), and by polarized light optical microscopy (PLOM) and Shore D hardness. The incorporation and functionalization of CNT into PHBV matrix did not change the Šesták and Berggren crystallization model; however, the lowest activation energy was obtained for the composite produced with CNT-GB, suggesting a better dispersion into the PHBV matrix. PLOM and Shore D hardness confirmed the results obtained in the kinetics study, showing the smallest crystallite size for CNT-containing nanocomposites and the highest hardness value for the composite produced with CNT-GB.

Comparison Between Isothermal Cold and Melt Crystallization of Polylactide/Clay Nanocomposites

2008 ◽  
Vol 8 (4) ◽  
pp. 1658-1668 ◽  
Author(s):  
Defeng Wu ◽  
Liang Wu ◽  
Lanfeng Wu ◽  
Bin Xu ◽  
Yisheng Zhang ◽  
...  
Keyword(s):  
Melting Behavior ◽  
Optical Microscope ◽  
Polymer Chains ◽  
Cold Crystallization ◽  
High Rate ◽  
Degree Of Crystallinity ◽  
Dominant Factor ◽  
Clay Nanocomposites ◽  
Melt Crystallization ◽  
Scanning Calorimetry

The isothermal cold and melt crystallization behavior of intercalated polylactide (PLA)/clay nanocomposites (PLACNs) were studied using differential scanning calorimetry (DSC), polarized optical microscope (POM), X-ray diffractometer (XRD) and Fourier Transform Infra-Red Spectrometer (FT-IR). The results show that the degree of crystallinity of PLA matrix decreases monotonously with increasing clay loadings for both the cold and melt crystallization. The cold crystallized sample shows a double melting behavior and lower melting temperature compared to that of melt-crystallized sample, especially in the presence of clay. The crystallization kinetics was then analyzed by the Avrami and Lauritzen-Hoffman methods for further comparison between these two crystallization behaviors. The results reveal that PLA and its nanocomposites present higher activation energy in melt crystallization than that in cold crystallization due to the reptation of entire polymer chains. The addition of clay facilitates the overall kinetics of melt crystallization, which is attributed to both the nucleation effect of clay and enhanced diffusion of PLA chains. However, for cold crystallization, only very small amounts of clay can slightly increase the kinetics, while larger amounts impede the process. The presence of clay leads to a diffusion-controlled growth of nucleation of PLA matrix in the cold crystallization process and, the hindrance effect of clay hence becomes the dominant factor gradually with increasing clay loadings in the case of high-rate nucleation.

Direct Experimental Study of Domain Structure In Magnetic Multilayers

1995 ◽  
Vol 384 ◽  
Author(s):  
V.I. Nikitenko ◽  
V.S. Gornakov ◽  
L.M. Dedukh ◽  
L.H. Bennett ◽  
R.D. McMichael ◽  
...  
Keyword(s):  
Domain Wall ◽  
Polarized Light ◽  
Optical Microscope ◽  
Magnetic Multilayers ◽  
Stray Field ◽  
Yttrium Iron ◽  
Plane Anisotropy ◽  
Light Optical Microscope ◽  
Iron Garnet ◽  
Indicator Film

ABSTRACTWe have applied a polarized light optical microscope in reflective mode with a Bi-substituted yttrium-iron-garnet indicator film with in-plane anisotropy for visualization of the magnetostatic fields produced by nanostructured magnetic CoNiCu/Cu electrodeposited multilayers. By analysis of the magneto-optical stray field image, detailed information is obtained not only on the as-grown multilayer magnetic structure but on its change during the magnetization reversal processes. The influences of crystal lattice defects and nonuniformity of the nonmagnetic spacers thicknesses on the domain wall nucleation and motion are studied. Peculiarities of the re-magnetization of antiferromagnetically exchange coupled multilayers are discussed, including real-time observations of domain wall creep in a constant applied field.

Liquid Crystalline Epoxy Resin Cured with Azomethine Hardening Compounds

2015 ◽  
Vol 749 ◽  
pp. 22-24
Author(s):  
Ho Kyoung Choi ◽  
Jae Hyun Choi ◽  
Hyeoung Seok Lee ◽  
Jae Sik Na
Keyword(s):  
Liquid Crystalline ◽  
Glycidyl Ether ◽  
Optical Microscope ◽  
Diglycidyl Ether ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Azomethine Group ◽  
H Nmr ◽  
Chemical Structures ◽  
Liquid Crystalline Epoxy

Bisphenol of 4,4’-dihydroxy-N-benzylidene-4-aminophenol containing azomethine group was synthesized via condensation of an aromatic amine namely 4-aminophenol with p-hydroxybenz aldehyde. It’s epoxy derivate and epicholorohydrin produced the new liquid crystalline diglycidyl ether of 4,4’-dihydroxy-N-benzylidene-4-aminophenol. A new type of liquid crystalline epoxy and azoemthine hardening agent are characterized at 300°C for 10 min, using c11z as a catalyst. The chemical structures were confirmed by FT-IR,1H-NMR. The curing reaction with 4,4’-dihydroxy-N-benzylidene-4-aminophenol were carried out in the ratio of glycidyl ether of 4,4’-dihydroxy-N-benzy lidene-4-aminophenol/azomethine hardening 1:0.8. The degree of crystallinity studied by X-ray diffractometer, differential scanning calorimetry (DSC) and polarized optical microscope (POM).

scholarly journals An insight on the process–property relationships of melt spun polylactic acid fibers

2019 ◽  
Vol 89 (23-24) ◽  
pp. 4959-4966 ◽  
Author(s):  
AM Ali ◽  
HM El-Dessouky
Keyword(s):  
Polylactic Acid ◽  
High Performance ◽  
Polarized Light ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Laser Diffractometry ◽  
Wide Range ◽  
Innovative Materials ◽  
The Degree Of Crystallinity

Polylactic acid (PLA) fibers are receiving growing interest as one of the recent innovative materials being developed for various applications. The inherent biodegradability of PLA makes it highly attractive for the biomedical and health care sectors. PLA fibers need to be partially and/or highly oriented to allow high performance and readiness for a wide range of manufacturability. In this study, the structure and properties of PLA fibers, manufactured at different spinning speeds, were studied. Laser diffractometry, polarized light microscopy, differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were used to determine the diameter, birefringence, molecular orientation, enthalpy and degree of crystallinity of as-spun and drawn PLA fibers. The results of DSC and XRD showed that the degree of crystallinity of the PLA fibers is significantly improved for the drawn PLA fibers compared to the as-spun fibers and leveled off in the case of changing the take-up speeds of drawn fibers.

scholarly journals Polyether Single and Double Crystalline Blends and the Effect of Lithium Salt on Their Crystallinity and Ionic Conductivity

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2097
Author(s):  
Jorge L. Olmedo-Martínez ◽  
Michele Pastorio ◽  
Elena Gabirondo ◽  
Alessandra Lorenzetti ◽  
Haritz Sardon ◽  
...  
Keyword(s):  
Ionic Conductivity ◽  
High Temperatures ◽  
Composition Range ◽  
Lithium Salt ◽  
Polarized Light ◽  
Crystallization Rate ◽  
Scanning Calorimetry ◽  
Blend Films ◽  
Nucleation Effect ◽  
The One

In this work, blends of Poly(ethylene oxide), PEO, and poly(1,6-hexanediol), PHD, were prepared in a wide composition range. They were examined by Differential Scanning Calorimetry (DSC), Polarized Light Optical Microscopy (PLOM) and Wide Angle X-ray Scattering (WAXS). Based on the results obtained, the blends were partially miscible in the melt and their crystallization was a function of miscibility and composition. Crystallization triggered phase separation. In blends with higher PEO contents both phases were able to crystallize due to the limited miscibility in this composition range. On the other hand, the blends with higher PHD contents display higher miscibility and therefore, only the PHD phase could crystallize in them. A nucleation effect of the PHD phase on the PEO phase was detected, probably caused by a transference of impurities mechanism. Since PEO is widely used as electrolyte in lithium batteries, the PEO/PHD blends were studied with lithium bis(trifluoromethanesulfonyl) imide (LiTFSI), and the effect of Li-salt concentration was studied. We found that the lithium salt preferentially dissolves in the PEO phase without significantly affecting the PHD component. While the Li-salt reduced the spherulite growth rate of the PEO phase within the blends, the overall crystallization rate was enhanced because of the strong nucleating effect of the PHD component. The ionic conductivity was also determined for the blends with Li-salt. At high temperatures (>70 °C), the conductivity is in the order of ~10−3 S cm−1, and as the temperature decreases, the crystallization of PHD was detected. This improved the self-standing character of the blend films at high temperatures as compared to the one of neat PEO.

scholarly journals Investigation on the Crystallization Behaviors of Polyoxymethylene with a Small Amount of Ionic Liquid

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 206 ◽  
Author(s):  
Qi Jiao ◽  
Qin Chen ◽  
Lian Wang ◽  
Hualin Chen ◽  
Yongjin Li
Keyword(s):  
Ionic Liquid ◽  
Polarized Light ◽  
Nucleating Agent ◽  
Crystal Nucleation ◽  
Scanning Calorimetry ◽  
Fine Crystal ◽  
Crystallization Behaviors ◽  
Nucleation Effect ◽  
Long Time ◽  
The Impact

Polyoxymethylene (POM) blends with excellent stiffness–toughness balance are successfully developed using Tributyl(octyl)phosphonium bis(trifloromethanesulfonyl) imide (TBOP-TFSI), one type of room-temperature ionic liquid, as the nucleating agent. Crystallization behaviors of POM blends have been studied by differential scanning calorimetry (DSC) and polarized light microscopy (PLM). The incorporation of TBOP-TFSI induces the crystal nucleation and fine crystal grain of POM, and also a much shorter hemi-crystalline time with only 0.5 wt% addition. The nucleation effect of ionic liquid leads to considerable improvement in the impact strength of POM blends while not sacrificing its tensile strength. Moreover, antistatic properties with a long-time stable performance are achieved by TBOP-TFSI addition as the electrical resistance reaches 1011 Ω/sq.

Microstructural Evolution of Synthesized Polyhydroxyalkanoates (PHAs) Corresponding to their Blends

2011 ◽  
Vol 312-315 ◽  
pp. 688-693 ◽  
Author(s):  
Pakawadee Kaewkannetra ◽  
Sarunya Promkotra
Keyword(s):  
Microstructural Evolution ◽  
Interfacial Adhesion ◽  
Corn Starch ◽  
Polarized Light ◽  
Recovery Process ◽  
Optical Microscope ◽  
Melting Transition ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Poor Adhesion

Biopolymers of polyhydroxyalkanoates (PHAs) are produced by pure bacterial strain of Alcaligenes eutrophus TISTR 1095 via batch fermentation using sugarcane juice as a carbon source, and yielded up to 21% (w/w) after recovery process. The PHAs are blended with bio-based materials such as tapioca and corn starch including glycerol and methanol to improve their microstructures. The combination of various plasticizers with PHAs is studied in different ratios. The PHAs and starch are mixed for 3% w/v and 30% w/v in hot chloroform, respectively. The varieties of PHAs to starch solution ratios are situated for casting as of films. The PHAs blended films are characterized by polarized light microscopy, differential scanning calorimetry (DSC) and x-ray diffractometry (XRD). The initial PHAs indicate remarkably crystalline structure with cross-polarized light on optical microscope. Macroscopic scales of their films are very brittle and flexible. However, their microscopic scales present small patches of particular components from each starch. Immiscibility of the blends is gradually increased on adding the starch portions. Additional glycerol shows more strongly interfacial adhesion between starch and PHAs, and methanol produces specifically thin films. Melting transition temperatures of blended films are slightly higher than the biosynthesized PHAs as examined by DSC. Corn starch mixture causes highly brittle films than tapioca mixtures, which indicates poor adhesion between corn starch and the PHAs. This result is correspondent to their highly crystallinity from diffractogram. Microstructural evolution of the blended films is increased slightly crystallinity by the solution casting.

Effects of Mesophase Pitch Pre-Oxidation on Structure and Flexural Strength of 2D C/C Composites

2013 ◽  
Vol 774-776 ◽  
pp. 654-659
Author(s):  
Zhi Hai Feng ◽  
Xiu Jun Liu ◽  
Tong Qi Li ◽  
Zhen Fan
Keyword(s):  
Flexural Strength ◽  
Polarized Light ◽  
Optical Microscope ◽  
Oxidation Temperature ◽  
Mesophase Pitch ◽  
Strength Increase ◽  
Bending Tests ◽  
Three Point Bending ◽  
Light Optical Microscope ◽  
Strength Dependence

Two dimensional carbon/carbon composites (2D C/C) were prepared by the low temperature-heat molding technique with PAN based carbon fabric as reinforcement and pre-oxidation mesophase pitch as matrix precursors. The effect of pre-oxidation for mesophase pitch on microstructure and flexural strength of 2D C/C composites has been evaluated using polarized light optical microscope, scanning electron microscope and three-point bending tests. As pre-oxidation temperature rising, the softening point of mesophase pitch increases, oxygen-containing functional groups increases as well, QI (quinoline insoluble) content increases significantly. The flexural strength dependence of pre-oxidation temperature has been studied and correlated with microstructure of 2D C/C composites. Results show that flexural strength increase when the pre-oxidation temperature rising, and meet its peak at 140°C, reached 44.7514MPa.

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